Certain vehicles can be powered using one or more high-voltage electric traction motors. Hybrid electric vehicles (HEV) having a full hybrid powertrain selectively use an internal combustion engine, either alone or in combination with the traction motor(s). A battery electric vehicle (BEV) uses a traction motor as the sole power source, while an extended-range electric vehicle (EREV) uses a gas engine to power a generator when additional electrical energy is required. Typically, a full HEV runs in an electric vehicle (EV) operating mode up to a threshold vehicle speed, and then automatically starts the engine upon reaching the threshold speed. Thereafter, the HEV transitions at least partially to engine torque.
The speeds of the various rotating members of an HEV, BEV, EREV, or EV powertrain, for instance an input speed to a transmission input member and/or a clutch slip speed of one or more of the clutches used within a transmission, may be controlled using a proportional-integral (PI) or a proportional-integral-derivative (PID)-capable controller. Different PI or PID controllers may be used to govern a speed of a given rotating member, as well as to damp any driveline oscillations or pulsations. A state observer can be used as part of the overall control law to provide state estimation within a particular physical system, e.g., the transmission, using various input and output parameters, as well as any required linear or other suitable state equations. In some vehicles, a common state space control law may be applied to both the speed control torque and the driveline damping control torque.